1-1-1-1-1-1-1-1-1-1-1-1-1-1 From: Paul Jarvis <p.jarvis@xxxxxxxxxx> Dear colleagues, We are delighted to invite you to join us for the next instalment of the *Ashvances in Tephra Hazard Modelling* seminar series, organised by the IAVCEI Commission for Tephra Hazard Modelling. The time for this seminar will be *01:00 UTC *on* 16 September 2025*. Please use this time zone converter <https://urldefense.com/v3/__https://www.timeanddate.com/worldclock/converter.html?iso=20250916T010000&p1=103&p2=18&p3=224&p4=1440&p5=108&p6=236&p7=122&p8=248&p9=240&p10=264__;!!IKRxdwAv5BmarQ!eCqhMDlL4JhE7EGPRu47f8nvt4tFEeaYsrYuNcBbX45mlpEsqAebw1gCeNcul2vcBsRXPjEHbpNbVIEGCk_ZvZ9efA$> to check the time of the event in your time zone. It is our pleasure to welcome, Valerie Olfindo (University of Queensland) and *Heather Craig *(University of Canterbury) as our speakers. They will be presenting: - Valerie Olfindo: *Unveiling the drivers of the Taal 2020 explosive eruption via tephra microchemistry* - Heather Craig: *Understanding ashfall impacts and long-term recovery from the 15 January 2022 eruption of Hunga Tonga-Hunga Haâ??apai volcano, Kingdom of Tonga* Abstracts for the two talks can be found below. If you would like to attend the seminar, *please register here <https://urldefense.com/v3/__https://events.teams.microsoft.com/event/7078f16c-50d9-4c59-9935-f0c7e5ba3d72@f607a494-56fb-4073-8fc5-6daa9c5d38d7__;!!IKRxdwAv5BmarQ!eCqhMDlL4JhE7EGPRu47f8nvt4tFEeaYsrYuNcBbX45mlpEsqAebw1gCeNcul2vcBsRXPjEHbpNbVIEGCk_aZVBLKw$>* . We recognise that the time of this event will not be amenable to everyone. We aim to rotate our seminars around different time zones as much as possible to reach audience members from across the globe and give everyone an equal and fair chance to participate in the seminars. We are always looking out for new speakers in future seminars. We aim to hold a seminar every quarter (c. 3 months), with each seminar lasting for about an hour. Two speakers will be allocated 15-20-minute talks with 5-10 minutes for questions. The last 10 minutes will be kept for general discussions, e.g., how the Tephra Hazard Modelling Commission can serve you better, and socializing/networking. At least one of the talks will be by an early-career researcher, and we will use this seminar series to showcase the work of researchers with backgrounds underrepresented in volcanology. Time zones will be selected based on the location(s) of speakers and we will aim to rotate these as much as possible to reach audience members from across the globe and give everyone an equal and fair chance to participate in the seminars. We aim that by having two talks per seminar, each session will cover multiple topics, including but not limited to numerical modelling, field studies, laboratory experiments and risk communication/management. *Please use this form **https://forms.gle/z7LB3TJDWauD3qCs6 <https://urldefense.com/v3/__https://forms.gle/z7LB3TJDWauD3qCs6__;!!IKRxdwAv5BmarQ!ZYbhk9h-Mu55gmuoIMwvyIC8M7kzQzsnRi4gp6yn6R6g390Oz7FTA4cXbI5RMdelaV_WHtdXISDx-y_Zhg$>** to register your interest in being a speaker or suggest a student/colleague*. We particularly encourage (self-) nomination of diverse and early career scientists. We look forward to welcoming you to what promises to be a fantastic seminar. *Please don't forget that you can sign up to our commission and mailing list anytime at this link <https://urldefense.com/v3/__https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=IAVCEITHM&A=1__;!!IKRxdwAv5BmarQ!eCqhMDlL4JhE7EGPRu47f8nvt4tFEeaYsrYuNcBbX45mlpEsqAebw1gCeNcul2vcBsRXPjEHbpNbVIEGCk-tpW9w4g$>.* All the best, Paul (on behalf of the co-chairs of IAVCEIâ??s Tephra Hazard Modelling Commission) *Abstracts* *Valerie Olfindo*: *Unveiling the drivers of the Taal 2020 explosive eruption via tephra microchemistry* The explosive eruption of Taal Volcano on 12-13 January 2020 generated extensive tephra deposits (mainly volcanic ash) mantling nearby municipalities, and reaching Metro Manila around 100 km away. Analysis of these erupted magma fragments will aid in understanding eruption triggers and improving volcano monitoring forecasts. In this study, we present petrographic and geochemical data of the Taal Volcano 2020 tephra deposit to unveil the drivers of the eruption and identify eruptive phases based on stratigraphy and geochemistry. Our initial data indicate the rapid ascent of intermediate magma, which might have triggered the explosive eruption. The minor occurrence of less differentiated magma, suggesting mafic magma recharge may also have contributed to the eruption. *Heather Craig*: *Understanding ashfall impacts and long-term recovery from the 15 January 2022 eruption of Hunga Tonga-Hunga Haâ??apai volcano, Kingdom of Tonga* The 15 January 2022 Hunga Tonga-Hunga Haâ??apai eruption generated a tsunami and ashfall that had widespread impacts to human health, buildings, agriculture, and infrastructure across the Kingdom of Tonga (population ~108,000). Currently, there is limited data on impacts and recovery from ashfall in the South Pacific. To address this gap, fieldwork was conducted on the islands of Tongatapu and Haâ??apai in June 2023, August 2023, and August 2025, focussing on four main areas: 1) the collection of primary ashfall impact data; 2) understanding Tongan partner agenciesâ?? interests; 3) engaging with local existing projects and research directions; and 4) understanding recovery pathways and approaches. Interviews and stakeholder workshops were conducted focussing on knowledge transfer and planning preparedness resources. The main lessons identified related to: arrangements for rapid ash hazard characterisation to inform the emergency management response; the requirements for ongoing cleaning of remobilised ash, particularly from electrical transformers and stormwater systems; improving awareness of cascading impacts from areas affected by both ashfall and tsunami; and the need for Tonga-specific ashfall preparedness and response resources. 1-1-1-1-1-1-1-1-1-1-1-1-1-1 ------------------------------
